PHOTIC REACTIONS OF HONEY-BEE 355 



a trial, the bee was removed, and the remaming data called for 

 on each record were entered. The tracing was marked with 

 arrows to indicate its direction. Observations on the physical 

 condition of the animal and others of importance, which were 

 made from time to time, were also noted on the record. All the 

 records of a single animal were then filed away together, thus 

 affording a permanent record for further reference. 



Since it was desired to make a quantitative study of circus 

 movements, it was necessary to adopt some method whereby the 

 amount of turning exhibited by an animal, in a given trial or 

 group of trials, might be expressed as a single value. These 

 values have been stated in terms of average number of degrees 

 turned per centimeter of progress, and were obtained in the fol- 

 lowing manner. The length of the trail was first measured with 

 a map tracer. Several readings were taken until two were ob- 

 tained with a difference of less than 0.3 cm. These were then 

 averaged, and the result used in computations. Thus in figure 3, 

 the length of the or'ginal tracing is 26.95 cm. Since, however, 

 the records were on a scale of 1 to 6, and these in reproduction 

 have been reduced one half, the length of the text figure tracing 

 must be multiplied by (6x2=) 12 in order to obtain the dis- 

 tance actually traveled by the animal. 



The various turns or angular deflections of the trail were next 

 estimated by reference to the radii of the plan. It is obvious 

 that in traveling a curved course, the direction of locomotion at 

 any given instant is the tangent to the curve at that point. For 

 example, in figure 3 the initial direction of locomotion is shown 

 by the tangent at a. This direction is parallel to a radius. From 

 a, the tangent to the curve or the direction of locomotion rotates 

 continuously to the left until the point h is reached. At b the 

 tangent is parallel to a second radius, which makes with the radius 

 of initial parallelism an angle of I of 360° or 180°. (Each radius 

 forms angles of 45° or | of 360° with its adjacent radii.) In 

 other words, in traveling from a to b the axis of the animal's 

 body has rotated 180° to the left, or the animal has executed ^ 

 of a complete sinistral loop. Similarly, from 6 to c the course of 

 the animal makes If dextral loops; from c to d, | of a sinistral 



